[R-390] R-390A Improving Sensitivity by Tube Optimizing

[Larry H]

Many years ago, Roger Ruszkowski posted a procedure on our R-390 List Forum
that identified an important noise level criteria for the IF and AF
system.  This 30 db criteria is necessary in order to be able to get your
R-390A overall noise figure to a good point (< 1 uv sensitivity).  It is
not documented in any official documentation, but is elsewhere.  This is
important because if your rx does not meet the overall sensitivity
requirement, this is a very good place to start.  This test will help you
determine if the problem is in the IF/AF section or the RF section.  And,
if it is in either, how to optimize tube selection to obtain improved noise
levels.

I have used it many times over the years and appreciate having it very
much.  Thank you Roger.  It's in the r-390 list forum archives, his 'R-390A
Checklists' on our website in the 'Tutorials' section (first entry, newly
highlighted), in the 'Pearls' 'Sensitivity Alignment' section, and in the
Y2K R3 Tech Ref.  Unfortunately, it's not easy to find.  Here's where it's
at:

1.  Y2K R3 Tech Ref: Chapter 9 – Supplemental Repair Info - part 1, p.
9-15.  The 'Tube Optimization' follows through p. 9-19.
2.  Roger's 'R-390A Checklists' in the 'Tutorials' section in paragraph Q
on PP. 16 - 18.  RF Optimization is on PP. 25 & 26.
3.  The 'Pearls' 'Sensitivity Alignment' section has it on PP. 472 - 476.

I hope this makes it easier to use Roger's valuable procedure.

Regards, Larry